KEKS Pay

First public release, after two years installed on Croatian stores.

• QR code and app deep link on the checkout, GET redirect into the KEKS Pay app from the Commerce payment form.
• Bank callback at keks-pay/keks/processing and at Commerce's webhook URL: token check, amount matched to the order, idempotent for repeated callbacks.
• Checkout page polls the order every five seconds and moves on once it is paid.
• Refund from the order's Transactions tab with the 3DES request hash.
• Settings accept environment variables; Croatian translations for the control panel and the checkout strings.